Numerical analysis of the contamination influence on the parameters of gas flow through single-hole orifice meter
The influence of contamination on the parameters of air flow through single-hole orifice meter was investigated using computer fluid dynamics. The air flow was steady state, three-dimensional and turbulent. The main considered physical properties of air were density and dynamic viscosity. The standard k-ɛ turbulence model was used. Single-hole orifice meter with four different β parameters 0.5, 0.55, 0.6 and 0.7, was observed. Also, the influence of contamination formed in front of the single hole orifice meter with the same β parameters was analyzed. The pressure drop, singular pressure loss coefficient and discharge coefficient were analyzed. Two variations of the characteristics of the contamination, h=1.55 mm and r = 1.5 mm and h = 1.55 mm and r = 2.5 mm, were considered for analysis. Numerical simulations were performed using commercial software the Star CCM+. It was found that the contamination has influence on the change of pressure drop values, which directly affects the change of other parameters. The pressure drop and singular pressure loss coefficient of the orifice with contamination are smaller compared to the values for a pure orifice, whereby the measurement accuracy was reduced. Also, for cases of contamination, the discharge coefficient was increased, leading to a negative measurement error. At smaller distances of the contamination from the edge of the orifice, the percentage deviations in the values of the singular pressure loss and discharge coefficients increased.